US 2013/0234893 A1 has already disclosed a system comprising a mobile functional module which has a communication unit for communicating electronic data. The system also has a building infrastructure apparatus which is in the form of a fire and/or smoke detector, for example, and has a communication unit for communicating with the functional module. The system also comprises a control and/or regulation unit which is intended to infer at least a position of the functional module on the basis of an evaluation of communication between the functional module and the building infrastructure apparatus.